Comparing characterization of functionalized multi-walled carbon nanotubes by potentiometric proton titration, NEXAFS, and XPS

Since the discovery of carbon nanotubes (CNT), this material has been recognized as an attractive catalyst support. CNT must be functionalized before use as a catalyst support and typically this involves oxidation. However, the functional group distribution on the CNT is very complex mixture of groups and varies with oxidation agent used. Here a simple acid-base titration is introduced to characterize the oxygen functionalized CNT. By comparing characterization with near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) for both at the C and O K-edges, it can be demonstrated that potentiometric proton titration can be a fast and quantitative analysis for Brönsted acid functional groups on CNT.

Graphical AbstractThis paper compares characterization of functional groups on oxidized MWCNT by NEXAFS and XPS with potentiometric titration. Potentiometric titration can be a fast and routine analysis for Brönsted acid functional groups on CNT.Figure optionsDownload full-size imageDownload as PowerPoint slide